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TRANSCRIPT
BRIEF DESCRIPTION OF INCIDENT:
Location: NLK
Rig: S#5 E-1400
Type of mast: SKYTOP
On 17/04/2017 while arranging for Rig
down Mast, during initial preparation/testing
for mast down job a sound was heard at
Derrick floor. After investigation it was
found mast vertical pulley towards driller
side got damaged (shaft dislodged from
mast member) and same ODS pulley got
slightly bent.
DS
ODS:
Bent
Pulley
How it happened…
Mast Bull line To equalizer pulley
& connect with other side bull line
Mast Bull line
Horizontal pulley
Vertical pulley
(damaged)Mast
Rig Floor
Mast bull line to anchoring on
mast
Casing line to fast
end pulley
Draw-
works
“A” frame
“A” frame pulley
Casing line
Contd……..
Extent of Damage DS: Shaft dislodged from mast memberODS: pulley got slightly bent
6.91
m 6.91
m
Possible reason(s)
Already existing crack in the weld joint between shaft & mast
member. It was not visible as rig was painted in its earlier
location.
1# After inspection it was decided to remove
shaft assembly and replace with a new one.
2# A work programme was developed in
consultation with OEM, BHEL- Hyderabad.
Repairing job on damaged pulley:
1) Inaccessibility
2) Elevation
& to overcome this,
1) A platform was
fabricated just
below the pulley
2) Transport crane
to hold the Safety
metal cage at
elevated position
at different angle.
But Constrains for carrying out job:
Working
platform
Metal
cage
Contd…..NDT was carried out on shaft, mast members.Observed crack on the Driller’s side shaft.
Crack
Contd…..
Fabricated new web plate. shaft along with web
plate align with mast member
This end
welded
here
DURING CUTTING & WELDING JOB
…….safety precaution against spark, fire….
As Loc.NLK was a gas well
(5k X-mas tree, flowing at
1400psi). Proper safety
procedure followed during
cutting/welding job,
- Well kept shut-in.
-Regularly gas reading was
checked in working areas.
-Fire extinguishers are kept
ready at D/F
-Running water kept on for
cooling near by well head areas.
After final welding, Carried out NDT of all load bearing points of
the newly done welding job. NDT was found OK.
&
BHEL, Hyderabad expert thoroughly examining the entire job.
Mast was lowered on 02/05/17 & placed on OFT.
****Please note:
--So far, What ever job carried out on S#5 mast was only
for carrying out mast down operation.
-- To put S#5 mast in operation again a details repairing
job was already worked out with OEM,BHEL-
HYDERABAD.
--Job is already started at NIA (From 18/05/17).
As per BHEL engineer job will be completed by
22/05/17.
Lesson learned /Remedial measures:-
--Before carrying out RU operation, at least once in a
year to carry out NDT of all load bearing points prior
to mast up operation
(i) Bull line anchoring point on mast
(ii) mast pulley(s) connection points on mast
(iii) dead end anchoring point.
It was already implemented at S#4, Loc-HYQ &
S#3, Loc-HYV
(iv) thoroughly inspection of bull line before R/Up
operation (Visual inspection already in place).
Proper health check up of our rigs by third party
expert. (e.g. DNV-GL at present is carrying out the
similar job for ONGCL in Sibsagar)